The present invention relates to an art of peeling a thin film from a base plate and discharging the peeled film.
In a printed circuit board for an electronic appliance such as a computer, wirings are made of copper or the like in a prescribed pattern on at least one side of an electrically insulating base plate. The printed circuit board is manufactured in a process described below. A stratified body consisting of a photosensitive resin layer and a light-transmissible resin film, which is a cover film for protecting the resin layer, is first adhered, under heat and pressure, to an electroconductive layer on the electrically insulating base plate. A wiring pattern film is then overlaid on the stratified body. The photosensitive resin layer is exposed to light through the wiring pattern film and the cover film for a prescribed time. The pattern film and the cover film are thereafter removed. The photosensitive resin layer is then developed so that an etching pattern mask is formed. Thereafter, the unnecessary portion of the electroconductive layer is removed by etching, and the remaining portion of the photosensitive resin layer is also removed. The printed circuit board having the wirings in the prescribed pattern is thus manufactured. In the process of manufacturing the printed circuit board, the cover film needs to be peeled from the photosensitive resin film before the resin film exposed to the light is developed. Since the peeling is performed by a human hand and the film is thin, the person needs to be dextrous and skilled enough to prevent the photosensitive resin film from being damaged or destroyed due to stress concentration or the like in the peeling. For that reason, an automatic thin film peeling machine for automatically peeling the cover film was developed. In the machine, a portion of the cover film of the stratified body adhered to the base plate is automatically lifted up by a needle, a brush, a knurled instrument or the like, and a fluid is then automatically blown onto the lift-up portion to peel the whole cover film. The cover film peeled by the fluid blown onto it is temporarily held on a peeling direction setting plate so that the cover film is thereafter entirely peeled from the base plate while being conveyed by a thin film conveyor including two conveyance belts which pinch the cover film in order to peel and convey the film. The thin film conveyor is coupled to the automatic thin film peeling machine or built therein. The cover film peeled and conveyed by the conveyor is discharged into a discharged thin film container.
An automatic thin film peeling machine disclosed in the Japanese Application No. 38880/86 made by the present applicant has an upper and lower discharged thin film containers over and under a base plate conveyance passage, respectively. A cover film peeled from the lower side of a base plate is discharged into the lower discharged thin film container, while a cover film peeled from the upper side of the base plate is discharged into the upper discharged thin film container. Since the thin film containers are disposed in a three-dimensional manner, the machine is compact. The upper cover film peeled from the upper side of the base plate is conveyed to the upper inlet opening of the upper discharged thin film container by the conveyance belt units of a thin film conveyor, and thereafter discharged into the container. The upper cover film is pinched between the conveyance belt units while being conveyed by them. Since the conveyance belt units are made long enough to correspond to the height of the upper discharged thin film container, a small tension difference is likely to occur between conveyance belts facing each other across the cover film, to often cause the film to undergo improper conveyance such as jamming. This is a problem. Since the upper discharged thin film container is located above the base plate conveyance passage it is troublesome and inefficient to handle the container to perform the dumping of the discharged cover film or do the like. This is another problem. If the upper discharged thin film container is made of a metal such as stainless steel, the container is heavy enough to greatly increase the problems and the inefficiency.
In order to solve the problems, the thin film conveyor of an automatic thin film peeling machine disclosed in the Japanese Patent Application No. 315552/87 made by the present applicant was developed. A cover film from the upper side of a base plate is conveyed and discharged by the first and second conveyance belt units of the thin film conveyor. The cover film is conveyed by the first conveyance belt unit while being pinched and peeled by the belt unit. The cover film is conveyed by the second conveyance belt unit while not being pinched by the belt unit but supported thereon. The second conveyance belt unit conveys the cover film in a direction extending across the direction of conveyance of the base plate. As a result, the automatic thin film peeling machine has feature that the length of the first conveyance belt unit which would be likely to cause the cover film to undergo improper conveyance is reduced. Since the second conveyance belt unit conveys the cover film in the direction extending across that of conveyance of the base plate, an upper discharged thin film container can be located in a relatively low position near the place where the conveyance of the cover film ends. For that reason, the machine has a feature that the upper discharged thin film container can be efficiently handled to perform the dumping of the discharged cover film or do the like.
Since each of the first and second conveyance belt units of the thin film conveyor of the automatic thin film peeling machine disclosed in the Japanese Patent Application No. 315552/87 is made of a plurality of rollers, a plurality of belts, a roller driver and so forth, the constitution of the conveyor is complicated. For that reason, the cost of manufacturing of the machine is high, and it is difficult to perform maintenance work on the machine. This is a problem. Since the second conveyance belt unit is made of reticulate belts and toothed rollers for revolving the belts, the problem arises markedly for the second conveyance belt unit.